The invention relates to an in-tank fuel filter for use in fuel tanks of motor vehicles and the like and more particularly to an in-tank fuel filter having conductive features which facilitate draining off to ground an electrical charge generated by passage of fuel through the filter.
For many years, fuel filters in motor vehicles and stationary power plant installations comprised a filter element disposed within a metallic housing at a convenient location in the fuel line. If the filter is installed in a motor vehicle, often times the filter would be disposed within the engine compartment. While hoses to and from the housing were generally rubber or other fuel tolerant flexible material and thus non-conductive, the housing was secured to a metal component or panel of the vehicle or installation and was thus grounded. Accordingly, any electrostatic charge generated by passage of the fuel through the filtration element was readily and safely grounded through the filter housing to the motor vehicle or other metallic component of the installation.
The constant examination and re-examination of vehicle weight reduction as well as continuing development of plastics and polymers has affected the fuel delivery and filtration systems of vehicles as it has most other motor vehicle systems. Rather than metal, filter housings are now frequently fabricated of a fuel tolerant plastic such as nylon. Such a construction typically results in the filtration element being electrically isolated from the vehicle ground. An electrostatic discharge (ESD) may result as a charge in the filtration element resulting from fuel passage therethrough increases and seeks ground. Frequently, such discharge occurs through the housing to the most proximate metallic vehicle body feature. Repeated discharge can result in perforation of the filter housing which is unacceptable.
It is now also common to fabricate the fuel tank from a fuel tolerant plastic or polymer material. Once again, the electrical insulating characteristics of the plastic or polymer tank isolate and insulate fuel system components disposed within the fuel tank from the vehicle ground.
A fuel filter specifically intended for in-tank installation which provides a path to ground from the filtration element to reduce the build up of electrostatic charges and the possibility of electrostatic discharges is thus both desirable and the subject of the present invention.
An in-tank fuel filter includes conductive features which provide a path to a grounded component of a motor vehicle to carry away static charges generated by passage of fuel through the filter. The filter includes a filter body and an in-situ molded conductive outlet fitting and runner assembly. The filter body includes a fabric layer having a plurality of conductive strands, threads or filaments which are in electrical contact with conductive runners which are molded onto the filter body and extend from the outlet fitting which is also electrically conductive. An electrically conductive path is thus provided from the conductive strands of the filter body, through the runners to the conductive outlet fitting which is attached to a conductive (typically metal) and grounded component of a fuel pump housing. An alternate embodiment includes a metal retaining ring which is mechanically engaged by and electrically connected to a metal register pin on the pump housing.
Thus it is an object of the present invention to provide a conductive in-tank fuel filter which reduces or eliminates electrostatic discharge within the fuel tank.
It is a further object of the present invention to provide a conductive in-tank fuel filter having an outer woven layer containing conductive strands or fibers.
It is a still further object of the present invention to provide an in-tank fuel filter having a layer of filtration material with conductive strands or fibers which are electrically connected to an electrically conductive outlet fitting.
It is a still further object of the present invention to provide an in-tank fuel filter having electrically conductive characteristics and a filtration element having plural layers.
It is a still further object of the present invention to provide an in-tank fuel filter having a conductive outlet fitting and conductive molded runners which are in electrical contact with conductive fibers disposed in filtration material.